About MC-Bauchemie Oxal VP I T

Oxal VP I T is best understood by what it deliberately does not try to be. Most injection grouts on the market are straight ordinary Portland cement (OPC) suspensions, chosen because they are cheap, fast-setting and strong. Oxal VP I T trades some of that strength for compatibility — it is built on a trass-lime-cement binder, where trass is a natural volcanic pozzolan that reacts with lime to form a mellower, more breathable binder chemistry closer to the traditional lime and pozzolanic mortars that historic stone and mixed masonry were actually built with. The result is a one-component, chloride-free grouting and injection glue with good flowability and a very low dynamic E-modulus (5,800 N/mm² at 28 days) — soft enough, relative to rigid OPC grout, to move with the natural stone and old masonry around it rather than fighting it.

For Space Arc’s clients across Delhi NCR and pan-India, that distinction matters most on heritage forts, havelis, stone temples, old load-bearing rubble-masonry walls and multi-layered facades where consolidation, not raw strength, is the job. Injecting a hard modern grout into a soft, centuries-old lime-and-stone wall routinely backfires — the stiff grout core takes all the load, shrinks slightly as it cures, and opens fresh cracks at the grout-to-stone interface that weren’t there before the “repair.” Oxal VP I T’s trass-lime-cement system, sulphate-resisting binder (per EN 197 part 1) and mortar-class M5 strength (per EN 998 part 2) are calibrated instead for filling cavities and voids, stabilising coarse- and mixed-grained masonry floors, and backfilling natural stone and mixed masonry that sees occasional dampness — work where the grout has to behave like a masonry material, not a structural concrete one.

The technical insight

The number worth understanding on this data sheet is the dynamic E-modulus: 5,800 N/mm² at 28 days. Ordinary structural cementitious grouts and repair mortars typically sit an order of magnitude stiffer — often 20,000 to 30,000+ N/mm². When a stiff grout is injected into a comparatively soft, old lime-and-stone wall, the grout core ends up carrying a disproportionate share of any subsequent movement (thermal cycling, minor settlement, moisture-driven expansion), and because it barely flexes, that stress concentrates at the interface with the surrounding stone — which is exactly where new hairline cracks then appear, undoing the “repair.” Oxal VP I T’s trass-lime-cement binder deliberately keeps stiffness low so the cured grout deforms in closer step with the masonry around it, spreading movement out instead of fighting it. Trass itself — a natural pozzolan — contributes to that low-alkalinity, sulphate-resisting chemistry (EN 197 part 1) while also reducing the free lime that can otherwise leach out and stain historic stone faces. It’s the same reasoning that underpins traditional lime-pozzolan mortars used for centuries in masonry conservation, translated into a pumpable, factory-controlled, one-component product.

Where it is used

• Consolidation grouting of natural stone masonry walls, forts and heritage facades
• Filling voids and cavities behind stone cladding, veneers and multi-layered masonry skins
• Backfilling and low-pressure injection grouting of rubble-core masonry walls
• Stabilising coarse- and mixed-grained masonry floors ahead of restoration
• Crack and void injection in mixed masonry built from combined stone and brick
• Pre-restoration consolidation of masonry ahead of repointing or replastering works
• Grouting of masonry retaining walls and structures that see periodic, non-permanent water saturation
• Void filling around anchors and dowels set into stone during conservation repairs

Key advantages

• Trass-lime-cement chemistry is compatible with old lime-bound masonry, avoiding the stiffness mismatch that plain OPC grouts cause in heritage stonework
• Very low dynamic E-modulus (5,800 N/mm²) lets the cured grout flex with natural stone and old masonry instead of forming a hard, crack-prone inclusion
• Chloride-free formulation is safe around embedded iron cramps, dowels and reinforcement in old masonry
• High sulphate-resisting binder per EN 197 part 1 suits masonry exposed to damp ground salts and occasional water saturation
• One-component product — only water is added on site, with no resin, hardener or accelerator to proportion and risk getting wrong
• Good flowability and low viscosity make it genuinely pumpable at low pressure through narrow packers, which matters when the substrate is fragile
• Roughly 60-minute working time at +20°C gives crews a realistic window for careful, low-pressure filling instead of a rushed pour
• 12-month shelf life in unopened bags simplifies stocking on phased conservation projects where work fronts open up over weeks, not days

Limitations & considerations

• Machine-mixing only — the manufacturer explicitly disallows hand mixing and part-batch mixing, so a pan or forced-action mixer must be arranged on site even for small jobs
• Comparatively modest strength (mortar class M5, ~9.5 N/mm² compressive at 28 days) — it stabilises and fills masonry voids but is not a structural repair mortar for load-bearing concrete elements
• Injection pressure is capped at 5 bar via worm pumps, which rules it out for high-pressure grouting of dense concrete or deep structural crack injection
• Working time (~60 minutes at +20°C) shortens further in peak Indian summer heat, demanding tighter batch discipline and possibly early-morning or evening placement
• Best results depend on a proper pre-injection survey and injection concept, as the manufacturer itself recommends — this is a specialist conservation-contractor product, not a casual DIY fix
• Sold only in 30 kg bags with no smaller pack, so very small heritage patch-repair jobs may see some material wastage

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie Oxal VP I T

Within MC-Bauchemie’s own Oxal range, Oxal VP I T sits at the natural-stone-friendly, low-E-modulus end of the family. Space Arc also stocks Oxal VP III HS, a highly sulphate-resistant, limestone-powder-free grout from the same range better suited to more aggressive sulphate-groundwater exposure where its extended application time and re-alkalising properties add value; project teams unsure which variant fits their masonry and exposure conditions should talk to Space Arc’s technical desk before ordering, since the two are not interchangeable. Looking outside the MC-Bauchemie stable, Fosroc’s closest offerings — Conbextra GP (general-purpose non-shrink cementitious grout) and its structural crack-injection resins — serve machine-base and structural-crack markets rather than heritage masonry consolidation, and neither is built on a trass-lime pozzolanic chemistry; a specifier choosing between them should do so on application fit (bedding/anchoring versus stone-masonry stabilisation) rather than treating them as swappable. For genuine natural-stone and heritage masonry consolidation work, Oxal VP I T’s combination of low stiffness and sulphate-resisting, chloride-free binder remains a fairly specialist choice without a like-for-like equivalent in most competing ranges.

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